package sike

import (
	"bufio"
	"bytes"
	"crypto/rand"
	"encoding/hex"
	"io"
	"math/big"
	"os"
	"strings"
	"testing"
)

var tdata = struct {
	name     string
	katFile  string
	PrB_sidh string
	PkB_sidh string
	PkB_sike string
	PrB_sike string
	PrA_sike string
	PkA_sike string
}{
	name:     "SIKEp503",
	katFile:  "etc/PQCkemKAT_434.rsp",
	PrB_sidh: "8626ED79D451140800E03B59B956F8210E556067407D13DC90FA9E8B872BFB0F",
	PkB_sidh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
	PrA_sike: "003271531CF27285B8721ED5CB46853043B346A66CBA6CF765F1B0EAA40BF602",
	PkA_sike: "BE0CB724207D42075EC1569F43FFB8178C64E1F3EAF9D914879B3B3CAD1D12048CBB72861CA0B72C16F65FB4DA98778D9F37CF1442147AE179A8D1099D77028740BD72DFC873A8D2F293A603E5C4A13F7668E8F5C363602A490D47F4F95B269706BDC8DFDEAD77026D9842BB8B5CC4BFB99AF75ED8E4A6994DD4BD5BA606D9EF21A38E26CC35AE5C57324CFE6C16B53D61AD985B37F4B1E2F11234C52A869E184008999358EC0D2B4F2F163A09D3BA9B83D7E5647B5BE92014286D5F0BCE0CA14417226462191D3F0D8587A3ADA2C561FBA5DFE938606476882472C64C9E07D6BDB6C51D59B7978C792383C0CCC28337192A30340742C82EFCB3693FE93FBDA870554CF40F2B176C831628FF339739EC87389A2DD261EE9C6AAFF09ECEFF6C5074D7755ACA4A9D937A1F3A7C31D82E606E6CC6AC90189C17899B13EB759761EEA35AAF74D0B7F2411031AF81B9B946AE2E154FC08F3BB3E2DDE5F52DBC0E1164DCE028EFA45B1D58F4B32EF016D4F995909D3E0F3F69B8115D35",
	PrB_sike: "4B622DE1350119C45A9F2E2EF3DC5DF50A759D138CDFBD64E82FCC97CA60CCB27BF6938C975658AEB8B4D37CFFBDE25D97E561F36C219A0E",
	PkB_sike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
}

/* -------------------------------------------------------------------------
   Helpers
   -------------------------------------------------------------------------*/
// Fail if err !=nil. Display msg as an error message
func checkErr(t testing.TB, err error, msg string) {
	if err != nil {
		t.Error(msg)
	}
}

// Utility used for running same test with all registered prime fields
type MultiIdTestingFunc func(testing.TB)

// Converts string to private key
func convToPrv(s string, v KeyVariant) *PrivateKey {
	key := NewPrivateKey(v)
	hex, e := hex.DecodeString(s)
	if e != nil {
		panic("non-hex number provided")
	}
	e = key.Import(hex)
	if e != nil {
		panic("Can't import private key")
	}
	return key
}

// Converts string to public key
func convToPub(s string, v KeyVariant) *PublicKey {
	key := NewPublicKey(v)
	hex, e := hex.DecodeString(s)
	if e != nil {
		panic("non-hex number provided")
	}
	e = key.Import(hex)
	if e != nil {
		panic("Can't import public key")
	}
	return key
}

/* -------------------------------------------------------------------------
   Unit tests
   -------------------------------------------------------------------------*/
func TestKeygen(t *testing.T) {
	var keyExp, keyGot [63 * 2 * 3]byte
	alicePrivate := convToPrv(tdata.PrA_sike, KeyVariant_SIDH_A)
	bobPrivate := convToPrv(tdata.PrB_sidh, KeyVariant_SIDH_B)
	expPubA := convToPub(tdata.PkA_sike, KeyVariant_SIDH_A)
	expPubB := convToPub(tdata.PkB_sidh, KeyVariant_SIDH_B)

	pubA := NewPublicKey(KeyVariant_SIDH_A)
	alicePrivate.GeneratePublicKey(pubA)
	pubB := NewPublicKey(KeyVariant_SIDH_B)
	bobPrivate.GeneratePublicKey(pubB)

	pubA.Export(keyExp[:])
	expPubA.Export(keyGot[:])
	if !bytes.Equal(keyExp[:], keyGot[:]) {
		t.Fatalf("unexpected value of public key A [\nGot: %X\nExp: %X]\n",
			keyExp, keyGot)
	}

	for i, _ := range keyExp {
		keyExp[i] = 0
		keyGot[i] = 0
	}

	pubB.Export(keyExp[:])
	expPubB.Export(keyGot[:])
	if !bytes.Equal(keyExp[:], keyGot[:]) {
		t.Fatalf("unexpected value of public key B [\nGot: %X\nExp: %X]\n",
			keyExp, keyGot)
	}
}

func TestImportExport(t *testing.T) {
	var err error
	var aBytes, bBytes [126 * 3]byte

	a := NewPublicKey(KeyVariant_SIDH_A)
	b := NewPublicKey(KeyVariant_SIDH_B)

	// Import keys
	aHex, err := hex.DecodeString(tdata.PkA_sike)
	checkErr(t, err, "invalid hex-number provided")

	err = a.Import(aHex)
	checkErr(t, err, "import failed")

	bHex, err := hex.DecodeString(tdata.PkB_sike)
	checkErr(t, err, "invalid hex-number provided")

	err = b.Import(bHex)
	checkErr(t, err, "import failed")

	a.Export(aBytes[:])
	b.Export(bBytes[:])

	// Export and check if same
	if !bytes.Equal(bBytes[:], bHex) || !bytes.Equal(aBytes[:], aHex) {
		t.Fatalf("export/import failed")
	}

	if (len(bBytes) != b.Size()) || (len(aBytes) != a.Size()) {
		t.Fatalf("wrong size of exported keys")
	}
}

func testPrivateKeyBelowMax(t testing.TB) {
	for variant, keySz := range map[KeyVariant]*DomainParams{
		KeyVariant_SIDH_A: &Params.A,
		KeyVariant_SIDH_B: &Params.B} {

		func(v KeyVariant, dp *DomainParams) {
			var blen = int(dp.SecretByteLen)
			var prv = NewPrivateKey(v)
			var secretBytes = make([]byte, prv.Size())

			// Calculate either (2^e2 - 1) or (2^s - 1); where s=ceil(log_2(3^e3)))
			maxSecertVal := big.NewInt(int64(dp.SecretBitLen))
			maxSecertVal.Exp(big.NewInt(int64(2)), maxSecertVal, nil)
			maxSecertVal.Sub(maxSecertVal, big.NewInt(1))

			// Do same test 1000 times
			for i := 0; i < 1000; i++ {
				err := prv.Generate(rand.Reader)
				checkErr(t, err, "Private key generation")

				// Convert to big-endian, as that's what expected by (*Int)SetBytes()
				prv.Export(secretBytes)
				for i := 0; i < int(blen/2); i++ {
					tmp := secretBytes[i] ^ secretBytes[blen-i-1]
					secretBytes[i] = tmp ^ secretBytes[i]
					secretBytes[blen-i-1] = tmp ^ secretBytes[blen-i-1]
				}
				prvBig := new(big.Int).SetBytes(secretBytes)
				// Check if generated key is bigger then acceptable
				if prvBig.Cmp(maxSecertVal) == 1 {
					t.Error("Generated private key is wrong")
				}
			}
		}(variant, keySz)
	}
}

func testKeyAgreement(t *testing.T, pkA, prA, pkB, prB string) {
	var e error
	var s1, s2 [126 * 3]byte

	// KeyPairs
	alicePublic := convToPub(pkA, KeyVariant_SIDH_A)
	bobPublic := convToPub(pkB, KeyVariant_SIDH_B)
	alicePrivate := convToPrv(prA, KeyVariant_SIDH_A)
	bobPrivate := convToPrv(prB, KeyVariant_SIDH_B)

	// Do actual test
	e = DeriveSecret(s1[:], bobPrivate, alicePublic)
	checkErr(t, e, "derivation s1")
	e = DeriveSecret(s2[:], alicePrivate, bobPublic)
	checkErr(t, e, "derivation s1")

	if !bytes.Equal(s1[:], s2[:]) {
		t.Fatalf("two shared keys: %d, %d do not match", s1, s2)
	}

	// Negative case
	dec, e := hex.DecodeString(tdata.PkA_sike)
	if e != nil {
		t.FailNow()
	}
	dec[0] = ^dec[0]
	e = alicePublic.Import(dec)
	if e != nil {
		t.FailNow()
	}

	e = DeriveSecret(s1[:], bobPrivate, alicePublic)
	checkErr(t, e, "derivation of s1 failed")
	e = DeriveSecret(s2[:], alicePrivate, bobPublic)
	checkErr(t, e, "derivation of s2 failed")

	if bytes.Equal(s1[:], s2[:]) {
		t.Fatalf("The two shared keys: %d, %d match", s1, s2)
	}
}

func TestDerivationRoundTrip(t *testing.T) {
	var err error
	var s1, s2 [126 * 3]byte

	pubA := NewPublicKey(KeyVariant_SIDH_A)
	prvA := NewPrivateKey(KeyVariant_SIDH_A)
	pubB := NewPublicKey(KeyVariant_SIDH_B)
	prvB := NewPrivateKey(KeyVariant_SIDH_B)

	// Generate private keys
	err = prvA.Generate(rand.Reader)
	checkErr(t, err, "key generation failed")
	err = prvB.Generate(rand.Reader)
	checkErr(t, err, "key generation failed")

	// Generate public keys
	prvA.GeneratePublicKey(pubA)
	prvB.GeneratePublicKey(pubB)

	// Derive shared secret
	err = DeriveSecret(s1[:], prvB, pubA)
	checkErr(t, err, "")

	err = DeriveSecret(s2[:], prvA, pubB)
	checkErr(t, err, "")

	if !bytes.Equal(s1[:], s2[:]) {
		t.Fatalf("Two shared keys: \n%X, \n%X do not match", s1, s2)
	}
}

// encrypt, decrypt, check if input/output plaintext is the same
func TestPKERoundTrip(t *testing.T) {
	// Message to be encrypted
	var msg = make([]byte, Params.MsgLen)
	var ct = make([]byte, kemSikeP503.CiphertextSize())
	for i, _ := range msg {
		msg[i] = byte(i)
	}

	// Import keys
	pkB := NewPublicKey(KeyVariant_SIKE)
	skB := NewPrivateKey(KeyVariant_SIKE)
	pk_hex, err := hex.DecodeString(tdata.PkB_sike)
	if err != nil {
		t.Fatal(err)
	}
	sk_hex, err := hex.DecodeString(tdata.PrB_sike)
	if err != nil {
		t.Fatal(err)
	}
	if pkB.Import(pk_hex) != nil || skB.Import(sk_hex) != nil {
		t.Error("Import")
	}

	err = encrypt(ct, rand.Reader, pkB, msg[:])
	if err != nil {
		t.Fatal(err)
	}
	var pt [40]byte
	pt_len, err := decrypt(pt[:], skB, ct)
	if err != nil {
		t.Fatal(err)
	}
	if !bytes.Equal(pt[:pt_len], msg[:]) {
		t.Errorf("Decryption failed \n got : %X\n exp : %X", pt, msg)
	}
}

// Generate key and check if can encrypt
func TestPKEKeyGeneration(t *testing.T) {
	// Message to be encrypted
	var msg = make([]byte, Params.MsgLen)
	var ct = make([]byte, kemSikeP503.CiphertextSize())
	var err error
	for i, _ := range msg {
		msg[i] = byte(i)
	}

	sk := NewPrivateKey(KeyVariant_SIKE)
	err = sk.Generate(rand.Reader)
	checkErr(t, err, "PEK key generation")
	pk := NewPublicKey(KeyVariant_SIKE)
	sk.GeneratePublicKey(pk)

	// Try to encrypt
	err = encrypt(ct, rand.Reader, pk, msg[:])
	checkErr(t, err, "PEK encryption")
	var pt [40]byte
	pt_len, err := decrypt(pt[:], sk, ct)
	checkErr(t, err, "PEK key decryption")

	if !bytes.Equal(pt[:pt_len], msg[:]) {
		t.Fatalf("Decryption failed \n got : %X\n exp : %X", pt, msg)
	}
}

func TestNegativePKE(t *testing.T) {
	var msg [40]byte
	var err error
	var ct = make([]byte, kemSikeP503.CiphertextSize())

	// Generate key
	pk := NewPublicKey(KeyVariant_SIKE)
	sk := NewPrivateKey(KeyVariant_SIKE)
	err = sk.Generate(rand.Reader)
	checkErr(t, err, "key generation")

	sk.GeneratePublicKey(pk)

	// bytelen(msg) - 1
	err = encrypt(ct, rand.Reader, pk, msg[:Params.KemSize+8-1])
	if err == nil {
		t.Fatal("Error hasn't been returned")
	}
	for _, v := range ct {
		if v != 0 {
			t.Fatal("Returned ciphertext must be not changed")
		}
	}

	// KemSize - 1
	var pt [40]byte
	pt_len, err := decrypt(pt[:], sk, msg[:Params.KemSize+8-1])
	if err == nil {
		t.Fatal("Error hasn't been returned")
	}
	if pt_len != 0 {
		t.Fatal("Ciphertext must be nil")
	}
}

func testKEMRoundTrip(t *testing.T, pkB, skB []byte) {
	ct := make([]byte, kemSikeP503.CiphertextSize())
	ss_e := make([]byte, kemSikeP503.SharedSecretSize())
	ss_d := make([]byte, kemSikeP503.SharedSecretSize())
	// Import keys
	pk := NewPublicKey(KeyVariant_SIKE)
	sk := NewPrivateKey(KeyVariant_SIKE)
	if pk.Import(pkB) != nil || sk.Import(skB) != nil {
		t.Error("Import failed")
	}

	checkErr(t, kemSikeP503.Encapsulate(ct, ss_e, pk),
		"error: Encapsulation during round-trip")
	checkErr(t, kemSikeP503.Decapsulate(ss_d, sk, pk, ct),
		"error: Decapsulation during round-trip")

	if !bytes.Equal(ss_e, ss_d) {
		t.Error("Shared secrets from decapsulation and encapsulation differ")
	}
}

func TestKEMRoundTrip(t *testing.T) {
	pk, err := hex.DecodeString(tdata.PkB_sike)
	checkErr(t, err, "public key B not a number")
	sk, err := hex.DecodeString(tdata.PrB_sike)
	checkErr(t, err, "private key B not a number")
	testKEMRoundTrip(t, pk, sk)
}

func TestKEMKeyGeneration(t *testing.T) {
	ct := make([]byte, kemSikeP503.CiphertextSize())
	ss_e := make([]byte, kemSikeP503.SharedSecretSize())
	ss_d := make([]byte, kemSikeP503.SharedSecretSize())

	// Generate key
	pk := NewPublicKey(KeyVariant_SIKE)
	sk := NewPrivateKey(KeyVariant_SIKE)
	checkErr(t, sk.Generate(rand.Reader), "error: key generation")
	sk.GeneratePublicKey(pk)

	// calculated shared secret
	checkErr(t, kemSikeP503.Encapsulate(ct, ss_e, pk),
		"encapsulation failed")
	checkErr(t, kemSikeP503.Decapsulate(ss_d, sk, pk, ct),
		"decapsulation failed")

	if !bytes.Equal(ss_e, ss_d) {
		t.Fatalf("KEM failed \n encapsulated: %X\n decapsulated: %X", ss_d, ss_e)
	}
}

func TestNegativeKEM(t *testing.T) {
	ct := make([]byte, kemSikeP503.CiphertextSize())
	ss_e := make([]byte, kemSikeP503.SharedSecretSize())
	ss_d := make([]byte, kemSikeP503.SharedSecretSize())

	pk := NewPublicKey(KeyVariant_SIKE)
	sk := NewPrivateKey(KeyVariant_SIKE)
	checkErr(t, sk.Generate(rand.Reader), "error: key generation")
	sk.GeneratePublicKey(pk)

	checkErr(t, kemSikeP503.Encapsulate(ct, ss_e, pk),
		"pre-requisite for a test failed")

	ct[0] = ct[0] - 1
	checkErr(t, kemSikeP503.Decapsulate(ss_d, sk, pk, ct),
		"decapsulation returns error when invalid ciphertext provided")

	if bytes.Equal(ss_e[:], ss_d) {
		// no idea how this could ever happen, but it would be very bad
		t.Error("critical error")
	}

	// Try encapsulating with SIDH key
	pkSidh := NewPublicKey(KeyVariant_SIDH_B)
	prSidh := NewPrivateKey(KeyVariant_SIDH_B)
	err := kemSikeP503.Encapsulate(ct, ss_e, pkSidh)
	if err == nil {
		t.Error("encapsulation accepts SIDH public key")
	}
	// Try decapsulating with SIDH key
	err = kemSikeP503.Decapsulate(ss_e, prSidh, pk, ct)
	if err == nil {
		t.Error("decapsulation accepts SIDH private key key")
	}
}

// In case invalid ciphertext is provided, SIKE's decapsulation must
// return same (but unpredictable) result for a given key.
func TestNegativeKEMSameWrongResult(t *testing.T) {
	ct := make([]byte, kemSikeP503.CiphertextSize())
	ss_e := make([]byte, kemSikeP503.SharedSecretSize())
	ss_d1 := make([]byte, kemSikeP503.SharedSecretSize())
	ss_d2 := make([]byte, kemSikeP503.SharedSecretSize())

	sk := NewPrivateKey(KeyVariant_SIKE)
	pk := NewPublicKey(KeyVariant_SIKE)

	// generate keys
	checkErr(t, sk.Generate(rand.Reader), "error: key generation")
	sk.GeneratePublicKey(pk)

	checkErr(t, kemSikeP503.Encapsulate(ct, ss_e, pk),
		"pre-requisite for a test failed")

	// make ciphertext wrong
	ct[0] = ct[0] - 1
	checkErr(t, kemSikeP503.Decapsulate(ss_d1, sk, pk, ct),
		"pre-requisite for a test failed")

	// second decapsulation must be done with same, but imported private key
	var expSk = make([]byte, sk.Size())
	sk.Export(expSk)

	// creat new private key
	sk = NewPrivateKey(KeyVariant_SIKE)
	checkErr(t, sk.Import(expSk),
		"import failed")

	// try decapsulating again. ss2 must be same as ss1 and different than
	// original plaintext
	checkErr(t, kemSikeP503.Decapsulate(ss_d2, sk, pk, ct),
		"pre-requisite for a test failed")

	if !bytes.Equal(ss_d1, ss_d2) {
		t.Error("decapsulation is insecure")
	}

	if bytes.Equal(ss_e, ss_d1) || bytes.Equal(ss_e, ss_d2) {
		// this test requires that decapsulation returns wrong result
		t.Errorf("test implementation error")
	}
}

func testKeygen(t *testing.T, pk, sk []byte) {
	var pubKeyBytes [126 * 3]byte
	// Import provided private key
	var prvKey = NewPrivateKey(KeyVariant_SIKE)
	if prvKey.Import(sk) != nil {
		panic("sike test: can't load KAT")
	}

	// Generate public key
	pubKey := NewPublicKey(KeyVariant_SIKE)
	prvKey.GeneratePublicKey(pubKey)
	pubKey.Export(pubKeyBytes[:])
	if !bytes.Equal(pubKeyBytes[:], pk) {
		t.Fatalf("KAT keygen form private failed\nExp: %X\nGot: %X\n", pubKeyBytes[:], pk)
	}
}

func TestKeyAgreement(t *testing.T) {
	testKeyAgreement(t, tdata.PkA_sike, tdata.PrA_sike, tdata.PkB_sidh, tdata.PrB_sidh)
}

// Same values as in sike_test.cc
func TestDecapsulation(t *testing.T) {

	var sk = [56]byte{
		0xDB, 0xAF, 0x2C, 0x89, 0xCA, 0x5A, 0xD4, 0x9D, 0x4F, 0x13,
		0x40, 0xDF, 0x2D, 0xB1, 0x5F, 0x4C, 0x91, 0xA7, 0x1F, 0x0B,
		0x29, 0x15, 0x01, 0x59, 0xBC, 0x5F, 0x0B, 0x4A, 0x03, 0x27,
		0x6F, 0x18}

	var pk = []byte{
		0xCA, 0x38, 0x7A, 0x45, 0xF8, 0xA7, 0xFB, 0xE5, 0x97, 0xB0,
		0x5B, 0xE4, 0x95, 0xDC, 0x38, 0xFA, 0xFC, 0x9B, 0xB3, 0xD1,
		0x79, 0xF8, 0x7D, 0x54, 0x0A, 0xD9, 0xE0, 0x64, 0xE3, 0xED,
		0x4D, 0x23, 0xD2, 0x86, 0x0D, 0x84, 0x0C, 0x44, 0x14, 0xE4,
		0x6B, 0xB9, 0x35, 0xBA, 0x70, 0x2A, 0x90, 0x92, 0xAA, 0x90,
		0x34, 0x81, 0x9F, 0xC7, 0x99, 0xD5, 0xB2, 0x2D, 0xD0, 0xBE,
		0xC9, 0x3B, 0x25, 0x8F, 0x49, 0x18, 0xFE, 0xDB, 0xE3, 0x60,
		0x04, 0x89, 0xB3, 0xC8, 0x8D, 0x2C, 0xC3, 0x35, 0x79, 0x45,
		0x56, 0x03, 0x3C, 0xA2, 0x93, 0xDC, 0xE1, 0x1E, 0x98, 0x50,
		0xB1, 0x65, 0xB9, 0x71, 0x8E, 0xB2, 0xBF, 0x93, 0x06, 0xDF,
		0x55, 0xE3, 0xC9, 0xF9, 0x53, 0xB4, 0x05, 0x70, 0xF3, 0x7D,
		0xE1, 0xE8, 0x78, 0x46, 0x93, 0x80, 0xBD, 0xBA, 0x7A, 0xE7,
		0x66, 0x67, 0x6D, 0x99, 0xAD, 0x02, 0x5E, 0xD2, 0xFE, 0x59,
		0x09, 0xB5, 0xF7, 0xB1, 0x60, 0x04, 0x59, 0x74, 0x21, 0x09,
		0x66, 0x6A, 0x2C, 0x94, 0xAC, 0x78, 0x7F, 0xA5, 0x4E, 0x58,
		0x07, 0xC4, 0xF2, 0x3F, 0x9C, 0x3E, 0xAB, 0x68, 0x83, 0xC4,
		0x8C, 0x3C, 0xBB, 0x1B, 0x41, 0xBE, 0x26, 0x7C, 0xD0, 0xB1,
		0xA8, 0xED, 0x3B, 0xA5, 0xD2, 0xAE, 0x4A, 0x44, 0xF8, 0xD6,
		0x31, 0xB4, 0x06, 0x78, 0x61, 0x3C, 0xBA, 0xE8, 0x1A, 0x20,
		0xF7, 0xE8, 0x11, 0x7D, 0x2C, 0xBC, 0xE6, 0x29, 0xD1, 0x73,
		0xCC, 0x68, 0x5A, 0x4A, 0x6F, 0x43, 0x4C, 0x6E, 0xEC, 0xB8,
		0x16, 0x9A, 0xE1, 0x82, 0x37, 0xC2, 0xAE, 0xD7, 0x2A, 0xD6,
		0xCC, 0x19, 0x6C, 0x9E, 0xD1, 0xBD, 0x6C, 0x74, 0x9A, 0x4C,
		0xA3, 0x6C, 0x4A, 0xAA, 0xB5, 0x99, 0x5F, 0xE9, 0x68, 0x0F,
		0x73, 0x2B, 0x44, 0x7D, 0x66, 0x4E, 0x63, 0x3C, 0x32, 0xEC,
		0x20, 0x03, 0xFF, 0xBE, 0xF3, 0x08, 0x0F, 0x11, 0xE2, 0x4B,
		0xF1, 0xD5, 0x12, 0xE2, 0x52, 0x66, 0x19, 0xE4, 0x8B, 0xA4,
		0x7E, 0x7F, 0x60, 0x27, 0x3B, 0x78, 0x6C, 0xC5, 0xBF, 0x58,
		0x6F, 0xFE, 0x05, 0xFC, 0x25, 0xF4, 0x12, 0x68, 0xAB, 0xA3,
		0x32, 0x75, 0x6A, 0x6A, 0xA6, 0x4E, 0x36, 0x42, 0x20, 0x17,
		0x2E, 0xBE, 0x7A, 0x0F, 0x78, 0x63, 0x3E, 0x5D, 0xBC, 0xB4,
		0xA0, 0xAC, 0xF3, 0xFE, 0x33, 0x49, 0x08, 0x62, 0xDC, 0x39,
		0xFF, 0xFD, 0x83, 0x02, 0x10, 0x8A, 0x86, 0xD7, 0x62, 0xE5,
		0xF2, 0x98, 0x7F, 0x8D, 0x79, 0x6A, 0xC4, 0x88, 0xD2, 0x84,
		0xC7, 0x3B, 0xEB, 0xC1, 0x6A, 0xE0, 0x7F, 0x42, 0x92, 0x25,
		0x0F, 0xA0, 0x35, 0xA5, 0xEF, 0x98, 0x4D, 0x41, 0xC5, 0x25,
		0x77, 0x35, 0x36, 0xA9, 0x0B, 0xAB, 0x43, 0x0C, 0x6C, 0xF1,
		0x31, 0x56, 0x17, 0x82, 0xD7, 0x00, 0x62, 0x1F,
	}

	var ct = []byte{
		0x7B, 0x1B, 0x9E, 0xFC, 0x2B, 0x63, 0x7A, 0x71, 0x19, 0x3A,
		0xAE, 0xC3, 0xDB, 0xEC, 0x20, 0x18, 0x27, 0x16, 0x64, 0xBF,
		0xE5, 0x5F, 0x48, 0x75, 0xA1, 0xAE, 0xF1, 0x92, 0x40, 0x77,
		0xB5, 0xF0, 0x85, 0x69, 0x8E, 0x02, 0x1A, 0x64, 0x94, 0x89,
		0xA0, 0xEE, 0xDA, 0xDB, 0x07, 0xE5, 0xE5, 0xFF, 0xE7, 0x01,
		0x5F, 0x5E, 0xC7, 0xD3, 0x3B, 0x27, 0xE1, 0x13, 0x9C, 0x01,
		0x33, 0x44, 0x35, 0x67, 0xEA, 0x14, 0xFE, 0x74, 0x03, 0x9F,
		0xD5, 0xE9, 0x3E, 0x58, 0x4A, 0xE3, 0xC2, 0x32, 0x22, 0x7A,
		0x80, 0xA0, 0x18, 0x3A, 0x31, 0xAB, 0xBE, 0x63, 0xD0, 0xA2,
		0xAB, 0x22, 0x28, 0x93, 0x17, 0x70, 0x79, 0x37, 0x4C, 0x55,
		0xC4, 0xCB, 0x0F, 0x0D, 0x21, 0xBC, 0x35, 0x6F, 0x35, 0x04,
		0x03, 0x5C, 0x23, 0xF6, 0x93, 0x4C, 0x98, 0x2D, 0x28, 0xB2,
		0x4D, 0x43, 0xA4, 0x27, 0xFD, 0x38, 0x70, 0x27, 0x2F, 0x46,
		0xA1, 0x25, 0x07, 0x86, 0x3A, 0x85, 0x50, 0x2E, 0x6B, 0x51,
		0x58, 0x8D, 0xE5, 0x52, 0xA4, 0x44, 0x1E, 0x7D, 0x3A, 0x9B,
		0x64, 0x89, 0xC8, 0x4F, 0x1C, 0x18, 0x98, 0xF5, 0xFE, 0x7F,
		0xCA, 0x3A, 0x84, 0x7C, 0x53, 0xA7, 0xA1, 0xF6, 0xB1, 0xB2,
		0xB5, 0xBC, 0xA5, 0x58, 0x31, 0xD4, 0xB2, 0x2E, 0x1D, 0xDE,
		0x3A, 0xD5, 0xB9, 0x70, 0xA3, 0xE6, 0xE9, 0x2C, 0x39, 0xF6,
		0xB5, 0x89, 0xDD, 0x14, 0x91, 0x31, 0x26, 0xE0, 0xAE, 0x66,
		0x30, 0x3A, 0x59, 0x57, 0xA3, 0xFF, 0xC1, 0x1F, 0x3B, 0xB8,
		0xA9, 0x9A, 0xB0, 0xAE, 0x2D, 0x70, 0x43, 0x38, 0x58, 0xF1,
		0xD5, 0xFC, 0x29, 0x6A, 0x49, 0xD3, 0x2E, 0x57, 0xA7, 0x16,
		0x7A, 0x2A, 0x06, 0x00, 0x39, 0x67, 0xCB, 0xA8, 0xB4, 0x26,
		0xC3, 0x4B, 0xD5, 0x15, 0x83, 0x95, 0xD9, 0xCC, 0x50, 0x1A,
		0x23, 0x00, 0xFF, 0xFE, 0x00, 0xFC, 0x99, 0x28, 0x38, 0xE8,
		0x60, 0xF0, 0xFD, 0x12, 0xD3, 0x22, 0x26, 0x8E, 0x1F, 0xED,
		0x11, 0x23, 0xB3, 0x56, 0x2A, 0x94, 0xE0, 0x1A, 0xE1, 0x25,
		0x6B, 0x1C, 0x5A, 0xB0, 0x15, 0xA8, 0xA5, 0xF8, 0x76, 0xA9,
		0x1F, 0x4E, 0xF1, 0x01, 0xC5, 0x12, 0x25, 0x8C, 0x1C, 0x10,
		0x02, 0xAF, 0x0E, 0x5E, 0xAC, 0x67, 0x84, 0x35, 0x98, 0xDD,
		0x99, 0x44, 0x15, 0x3B, 0x03, 0x41, 0x37, 0x10, 0x1F, 0x3A,
		0x36, 0xFF, 0x0A, 0x47, 0xCA, 0x22, 0xA4, 0x36, 0xEB, 0x4C,
		0x7D, 0x9B, 0x9A, 0xBD, 0x13, 0x4C, 0x5A, 0x0E, 0xCD, 0x35,
		0xB3, 0x3A, 0xA7, 0x15, 0xFD, 0xEC, 0xEE, 0x37, 0x21, 0x25,
		0xB4, 0xCC, 0x20, 0x07, 0x7F, 0xA7, 0x9F, 0x0F, 0x97, 0x3C,
		0x26, 0x10, 0xE1, 0xE9, 0x3A, 0xF7, 0x53, 0x43, 0xC4, 0xCA,
		0x97, 0x54, 0x13, 0x59, 0x24, 0x72, 0xE3, 0x1D, 0xE7, 0x00,
		0x09, 0x61, 0x29, 0x5A, 0x53, 0x14, 0x5F, 0xAA, 0xF6, 0x6A,
		0xFA, 0x72, 0xCA, 0x79, 0xC6, 0xA4, 0x9B, 0xEF, 0xE5, 0x69,
		0x9E, 0x66,
	}
	var ss_exp = [24]byte{
		0x0F, 0x7E, 0x5A, 0x52, 0x19, 0x9E, 0x77, 0x87, 0x2E, 0x93,
		0x3A, 0xCB, 0x13, 0xD7, 0x96, 0xD6, 0x76, 0x27, 0xA6, 0x27,
		0xE9, 0x1D, 0xD4, 0x2A,
	}

	var prvObj = NewPrivateKey(KeyVariant_SIKE)
	var pubObj = NewPublicKey(KeyVariant_SIKE)

	if pubObj.Import(pk) != nil || prvObj.Import(sk[:]) != nil {
		t.Error("Can't import one of the keys")
	}

	res := make([]byte, kemSikeP503.SharedSecretSize())
	checkErr(t, kemSikeP503.Decapsulate(res, prvObj, pubObj, ct),
		"error: Decapsulation failed")

	if !bytes.Equal(ss_exp[:], res) {
		t.Error("Wrong decapsulation result")
	}
}

func readAndCheckLine(r *bufio.Reader) []byte {
	// Read next line from buffer
	line, isPrefix, err := r.ReadLine()
	if err != nil || isPrefix {
		panic("Wrong format of input file")
	}

	// Function expects that line is in format "KEY = HEX_VALUE". Get
	// value, which should be a hex string
	hexst := strings.Split(string(line), "=")[1]
	hexst = strings.TrimSpace(hexst)
	// Convert value to byte string
	ret, err := hex.DecodeString(hexst)
	if err != nil {
		panic("Wrong format of input file")
	}
	return ret
}

func TestKAT(t *testing.T) {
	ssGot := make([]byte, kemSikeP503.SharedSecretSize())
		testDecapsulation := func(t *testing.T, pk, sk, ct, ssExpected []byte) {
			var pubKey = NewPublicKey(KeyVariant_SIKE)
			var prvKey = NewPrivateKey(KeyVariant_SIKE)
			if pubKey.Import(pk) != nil || prvKey.Import(sk) != nil {
				panic("sike test: can't load KAT")
			}

			err := kemSikeP503.Decapsulate(ssGot, prvKey, pubKey, ct)
			if err != nil {
				panic("sike test: can't perform degcapsulation KAT")
			}

			if (err != nil) || !bytes.Equal(ssGot, ssExpected) {
				t.Fatalf("KAT decapsulation failed\n")
			}
		}
	f, err := os.Open(tdata.katFile)
	if err != nil {
		t.Fatal(err)
	}

	r := bufio.NewReader(f)
	for {
		line, isPrefix, err := r.ReadLine()
		if err != nil || isPrefix {
			if err == io.EOF {
				break
			} else {
				t.Fatal(err)
			}
		}
		if len(strings.TrimSpace(string(line))) == 0 || line[0] == '#' {
			continue
		}

		// count
		_ = strings.Split(string(line), "=")[1]
		// seed
		_ = readAndCheckLine(r)
		// pk
		pk := readAndCheckLine(r)
		// sk (secret key in test vector is concatenation of
		// MSG + SECRET_BOB_KEY + PUBLIC_BOB_KEY. We use only MSG+SECRET_BOB_KEY
		sk := readAndCheckLine(r)
		sk = sk[:Params.MsgLen+int(Params.B.SecretByteLen)]
		// ct
		ct := readAndCheckLine(r)
		// ss
		ss := readAndCheckLine(r)
		testKeygen(t, pk, sk)
		testDecapsulation(t, pk, sk, ct, ss)
		testKEMRoundTrip(t, pk, sk)
	}
}

/* -------------------------------------------------------------------------
Benchmarking
-------------------------------------------------------------------------*/

func BenchmarkKeygen(b *testing.B) {
	pk := NewPublicKey(KeyVariant_SIKE)
	prv := NewPrivateKey(KeyVariant_SIKE)
	prv.Generate(rand.Reader)

	for n := 0; n < b.N; n++ {
		prv.GeneratePublicKey(pk)
	}
}

func BenchmarkEncaps(b *testing.B) {
	pub := NewPublicKey(KeyVariant_SIKE)
	prv := NewPrivateKey(KeyVariant_SIKE)

	if prv.Generate(rand.Reader) != nil {
		b.FailNow()
	}
	prv.GeneratePublicKey(pub)

	var ct [24 + 378]byte
	var ss [16]byte

	for n := 0; n < b.N; n++ {
		kemSikeP503.Reset()
		kemSikeP503.Encapsulate(ct[:], ss[:], pub)
	}
}

func BenchmarkDecaps(b *testing.B) {
	var ct [24 + 378]byte
	var ss [16]byte

	pkA := NewPublicKey(KeyVariant_SIKE)
	prvA := NewPrivateKey(KeyVariant_SIKE)
	pkB := NewPublicKey(KeyVariant_SIKE)
	prvB := NewPrivateKey(KeyVariant_SIKE)

	if prvA.Generate(rand.Reader) != nil || prvB.Generate(rand.Reader) != nil {
		b.FailNow()
	}

	prvA.GeneratePublicKey(pkA)
	prvB.GeneratePublicKey(pkB)

	err := kemSikeP503.Encapsulate(ct[:], ss[:], pkA)
	if err != nil {
		b.FailNow()
	}

	for n := 0; n < b.N; n++ {
		kemSikeP503.Decapsulate(ss[:], prvA, pkB, ct[:])
	}
}

var kemSikeP503 KEM

func init() {
	kemSikeP503.Allocate(rand.Reader)
}